Voltage regulated direct view storage tube precollimation system



Aug. 5, 1969 BRQOKE ET AL 3,459,990

VOLTAGE REGULATED DIRECT VIEW STORAGE TUBE PHECOLLIMATION SYSTEM Filed July 27, 196'? fiv FIG. 3.

WITNESSES INVENTORS Donald C. Brooke and Irwin Albert m KQW ATTORNEY Y United States Patent O U.S. Cl. 315-14 4 Claims ABSTRACT OF THE DISCLOSURE A storage display system including a voltage regulated precollimation network integral with a direct view storage tube.

BACKGROUND OF THE INVENTION The invention relates to a storage display system which incorporates a storage display tube and a voltage regulated precollimati-on network integral with said display tube.

It has been the practice in some types of display storage tubes to install a voltage divider network integral with the tube for the purpose of providing factory rather than user adjusted potentials. In utilizing this system, the user need supply only one or two fixed potential-s to the network to insure that the display is set up properly in the field. The network is adjusted at the factory to provide proper electrode potentials when the user appliesthe fixed potentials. U.S. Patent 3,299,316 provides a voltage divider system in which the resistance ratios of the divider network may be varied in the field if necessary. Such an arrangement is useful in that it permits maintenance of optimum display quality throughout the tube life.

One of the shortcomings of the voltage divider network described in the above-mentioned patent is the inherent poor voltage regulation due to short term variations in the viewing gun beam current flowing through such a divider network. These changes in current produce voltage drops within the network and prevent proper potentials from being applied at the tube electrodes. This results in poor collimation of the reading or flooding beam.

It is an object of this invention to provide a voltage divider network integral to the display tube which has a high degree of voltage regulation.

It is a further object of this invention to provide a voltage divider network integral with the display tube which has a high degree of voltage regulation and maintains such regulation with changes in ambient temperature.

It is still a further object of this invention to provide a voltage network divider integral with the display tube having a high degree of voltage regulation to maintain substantially constant potentials for the flooding beam electrodes.

SUMMARY OF THE INVENTION In accordance with the invention, a voltage divider and regulated circuit is provided integral with a display storage tube to provide optimum potentials to the flood beam electrodes and maintain their potentials during operations.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a direct view storage tube system incorporating the invention;

FIG. 2 is a circuit illustrating the circuit associated with FIGURE 1 for voltage regulation; and

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FIG. 3 is a general sectional view illustrating the circuit components associated with the tube prior to encapsulation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is shown a conventional direct view storage tube 10 which includes an envelope 12 of a suitable material such as glass. The envelope 12 includes a neck portion 14 of a first diameter and a body portion 16 of larger diameter than said neck portion 14 with a face plate member 18 closing off the body portion 16 of the envelope '12. The neck portion 14 of the envelope 12 is closed off with a button stem member 20. Positioned on the inner surface of the faceplate 18 is an electron sensitive screen 22 of a suitable phosphor material which emits light in response to electron bombardment. A planar storage grid 24 is positioned in the body portion 16 of the envelope 12 of similar area as the display screen 22 and para lel to the screen 22. The storage grid 24 is comprised of an electrically conductive mesh with a dielectric coating. A suppressor grid 26 of an electrically conductive mesh is provided between the display screen 22 and the storage grid 24. A collector grid 28 of an electrically conductive mesh is provided on the opposite side of the storage grid 24 with respect to the suppressor grid 26. The potential of display screen 22 is about 10 kilovolts, the suppressor grid 26 is about volts, the storage grid 24 is about 15 volts and the collector 28 is about 265 volts. These potentials are all positive with respect to ground and flood gun cathode potential.

A conductive coating 29 of a material such as aquadag and referred to as the collimator electrode is provided on the inner surface of the body portion 16 and extends from a point adjacent the collector mesh 28 to the neck portion 14. The collimator electrode 29 operates at a potential of about volts positive with respect to ground.

Two write electron guns 3t and 32 are provided in the neck portion 14 of the envelope and generate penciltype electron beams in a well known manner. The electron beams from the electron guns 30 and 32 are deflected by suitable deflection means to scan a raster over the storage grid 24. A flood electron gun 34 is also positioned in the neck region of the envelope 12 adjacent the body portion 14. The flood electron gun 34 consists of at least a cathode 36, a control grid 38 and a screen grid 40. The cathode 36 is normally at ground potential. The control grid 38 is at a potential of about 6 volts negative with respect to ground and the screen grid 40 is at a potential of about 80 volts positive with respect to ground. The screen grid 40 may be connected to the collimator eletcrode 29. An electrical contact button 41 is provided through the wall of the envelope 12 for applying a potential to the collimator electrode 29. Another contact button 42 is provided for applying a potential from the exterior of the envelope 12 to the collector grid 28. An electrical conductive lead 44 is provided from the button 41 to the tube base 2% and an electrical lead 46 is provided from the anode button 42 to the tube base 20. The leads 44 and 46 are each connected to separate pins 21 provided in the tube base 20.

The circuit elements associated with the tube are mounted on the tube base 20 as illustrated in FIG. 3 between appropriate pins 21 and the unit is encapsulated with a magnetic shield 31 surrounding the major portions of the envelope 10.

Referring in detail to FIGURE 2, there is illustrated a regulation network which is associated with and encapsulated on the button stem member 20 as illustrated in FIGURE 3. The circuit includes a positive input terminal 70 to which a potential of about 265 volts with respect to ground is applied. A negative input terminal 72 is provided to which an input of a negative 50 to 100 volts DC is applied with respect to ground. A third terminal 74 is a reference input and is connected to flood gun cathode and operates at equipment ground potential. The positive input terminal 70 is connected to a pin 21 as sociated with the lead 46 which goes to the collector electrode 28. The collector 28 operates at a potential of a positive 265 volts. Connected across the terminals 70 and 74 is a resistor 50 and a Zener diode 52. The Zener diode 52 is of the type which has a breakdown potential of about a hundred volts. Connected in parallel with the diode 52 is a potentiometer 54 with the sliding contact 56 of the potentiometer 54 connected to the lead-in 44 which in turn connects to the collimator electrode 29. The value of the current limiting resistor 50 is about 50,000 ohms and the potentiometer 54 is about 50,000 ohms. The diode 52 having a rated reverse breakdown voltage of 100 volts at approximately 2.5 milliamperes is connected across the potentiometer 54. The voltage is in excess of the breakdown voltage of the diode 52 so that it conducts and draws current through the resistor 50. Any changes in current in the system result in the diode 52 drawing more or less current such that the voltage drop across the diode remains substantially constant. The potentiometer 54 can be varied to produce the required potential on the tube collimating electrode 29 which is at a potential of about 80 volts. The electrode current path is through a portion of the potentiometer 54 between the sliding contact 56 and the junction with the resistor 50 and the diode 52. This portion of the potentiometer 54 and the regulated voltage source is small compared to the resistance that would be between the electrode and the regulated source of voltage in the case of an unregulated network. The low resistance in the regulator circuit produces a much smaller voltage drop for the same variation of an electrode current and provides a regulator potential source.

If desired a thermistor or sensitor may be inserted in the circuit to compensate for voltage changes across the diode 52 due to changes in ambient temperature and is chosen so that the resultant voltage is substantially constant across the diode.

The reference contact 74 is connected to the cathode 36 of the flood gun. The negative input terminal 72 is connected through a resistor 66 of about 53,000 ohms and a diode 58 to the terminal 74. The diode 58 is a Zener diode having a voltage breakdown of about 50 volts. A resistor 62 and a resistor 64 connected in series are placed in parallel across the diode 58 and a lead 53 is connected from the common terminal of the resistors 62, 64 to the control grid 38 of the flood gun 34. The control grid 38 operates at a potential of about a negative 6 volts with respect to ground. Here again, as in the previous voltage regulation circuit, the diode 58 provides a regulated voltage source substantially constant with changes in current flowing within the circuit. Again a thermistor or other suitable temperature compensating device may be operatively associated with the diode 58 to provide voltage uniformity with changing ambient temperature.

It is quite obvious that other suitable voltage regulating circuits may be associated with the storage tube to provide suitable regulation. The resulting assembly permits the proper setup for operation by trained factory personnel and replacements of the system in the field are accomplished without degradation due to improper voltage or adjustment in the field. Any changes in the electrode currents throughout tube life have no degrading effect on the optics of the system.

What is claimed is:

1. A storage system comprising a storage tube, said tube comprising an envelope having at least a collector electrode, a collimator electrode and a flood electron gun therein, said flood gun including at least a cathode electrode and acontrol electrode, input terminals for said system including a positive DC potential terminal, a negative DC potential terminal and a common input terminal, said collector electrode connected to said positive DC terminal, said cathode connected to said common input terminal, a first impedance means operatively connected between said positive DC potential terminal and said common input for providing a predetermined potential to said collimator electrode, a second impedance means means operatively connected between said common input terminal and said negative DC terminal for providing a predetermined potential to said control grid, a first regulating means responsive to current and voltage changes connected between said positive DC terminal and said common input terminal for providing a substantially constant potential .to said first impedance means, a second regulating means responsive to current and voltage changes connected between said negative DC terminal and said common input terminal for providing a substantially constant potential to said second impedance means for regulating the potentials supplied to said control grid electrode and a member encapsulating said impedance means, said regulating means and a major portion of said envelope to provide an integral system.

2. The device set forth in claim '1 in which said first regulating means comprises a first diode connected between said positive DC potential terminal and said common input terminal, said second regulating means comprising a second diode connected between said negative DC potential terminal and said common input terminal.

3. The device set forth in claim 1 in which said first impedance means includes a first and second resistor connected in series across said positive DC potential terminal and said common input terminal and in which said second resistor is a potentiometer in which the movable tap is connected to said collimator electrode and one terminal of said second resistor is connected to said common input terminal and in which said first regulating means includes a diode connected in parallel with said second resistor.

4. The device set forth in claim 3 in which said diode has its anode electrode connected to said common input terminal and the cathode electrode connected to the remote terminal of said second resistor with respect to said common input terminal.

References Cited UNITED STATES PATENTS 2,728,872 12/ 1955 Smith 31512 2,818,524 12/1957 Smith et a1. 315-12 3,066,229 11/1962 Cody 315-44 X 3,299,316 1/1967 Wollrich 313- X RODNEY D. BENNETT, 111., Primary Examiner MALCOLM F. HUBLER, Assistant Examiner US. Cl. X.R. 3l512 

